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ASHS Certified Professional Horticulturists
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Administered by the ASHS Certified Professional Horticultural Board, (CPHB), a CPH certification is granted based on scholarly presentation, required participation in continuing education programs in particular areas of specialization, and work experience supported by references. Individuals certified by the CPHB have met educational and practical experience standards, subscribe to the CPH Code of Ethics, and qualify for identification and recognition as professionals of excellence in their field.

United States


Keith M. Backman, CPH
1511 Middleton St., Hanford, CA 93230
Phone: 559.584.8322
Areas of Expertise: Groundwater Quality; Soil Plant Analysis; Crop Quality; Saline Soils

Jim Browne, CPH
501 Dale View Ave., Belmont, CA 94002
Areas of Expertise: Plant ecology, ecological restoration, vegetation surveys, arboriculture.


Thomas Confal, CPH
14675 Moon Shadow Rd., Nevada City, CA 95959
Areas of Expertise: Pest Management; Irrigation; General Horticulture; Turf Management


Dawn A. De Vos, PhD, CPH
De Vos & Associates
1961 Main Street, PMB 148, Watsonville, CA 95076-3027
Phone: 831.685.1875
Area of Expertise: Crop Science, Crop Production, Crop Marketing, Crop Breeding


Neal E. De Vos, PhD, CPH
De Vos & Associates
1961 Main St., PMB 148, Watsonville, CA 95076-3027
Phone: 831.688.9577
Areas of Expertise: General Horticulture; Olericulture; Plant Breeding; Seed Production 


R. Stanley Grant, CPH
1015 Yosemite St., Turlock, CA 95380
Phone: 209.664.7656
Areas of Expertise: Viticulture; Soil Management; Crop Production; Farm Management 

Larry D. Knerr, CPH
Salinas, CA 93901
Phone: 831.455.4018
Areas of Expertise: General Horticulture; Plant Breeding; Plant Genetics; Weed Science

Michael D. McCullough, CPH
19310 Acclaim Drive
Salinas, CA 93908

Areas of Expertise: General and Ornamental Horticulture; Plant Pathology; Turfgrass Management 

Robert L. Mazalewski, CPH
PO Box 72809, Davis, CA 95617-2809
Phone: 530.902.8330
Areas of Expertise: General Horticulture; Ornamental Horticulture; Nursery Management 

Robert L. Mikkelsen, CPH
African Plant Nutrition Institute
4125 Sattui Court, Merced, CA 95348
Phone: 209.725.0382
Areas of Expertise: Soil Fertility, Plant Nutrition, Soil Chemistry, Fertilizer Use

Rob Mikkelsen is the Director of Communications for the African Plant Nutrition Institute, Headquartered in Morroco. He was previously Director of Western North America programs for the International Plant Nutrition Institute. He was previously Professor of Soil Science at North Carolina State University (NCSU) in Raleigh and Soil Chemist at the National Fertilizer Development Center at Muscle Shoals, Alabama. He is widely known for his research and expertise in nutrient management and writes widely on topics related to plant nutrition, nutrient management, environmental issues, and fertilizer technology.  In addition to being a Certified Professional Horticulturist, Rob is a Certified Crop Advisor. A native of California, Dr. Mikkelsen earned his B.S. degree in Agronomy/Soils at Brigham Young University and a PhD in Soil Science at University of California, Riverside. Rob regularly writes in his nutrient management blog.


Kerrie B. Badertscher, CPH
Otoké Horticulture LLC, Specialty Crop Consulting
PO Box 517, Allenspark, CO 80510
Areas of Expertise: Cannabis Consultant


Paul D. Orpello, CPH
Supervisor, Gardens and Horticulture
Hagley Museum and Library
Wilmington, DE
Areas of expertise: Organic and Historic Food Crop Production, Ecological Garden Design, Landscape Management, Propagation


Mary L. Lamberts, CPH
Dade Co. Coop. Ext.
18710 SW 288th St., Homestead FL 33030-2309
Phone: 305.248.3311, ext. 234
Areas of Expertise: International Horticulture; Olericulture; Tropical Crops 


Alicia J. Whidden, CPH
5110 Ralston Rd., Lakeland, FL 33811
Phone: 813.744.5519, ext. 134
Areas of Expertise: Plant Pathology; Small Fruit Culture 

Uday K. Yadav, CPH
HCS Inc.
764 Silverwood Drive, Lake Mary, FL 32746
Areas of Expertise: General Agronomy; Crop Production; General Horticulture; Turfgrass Management


John K. Mockus, CPH

714 S. River Rd., Naperville, IL 60540
Phone: 630.393.4554
Areas of Expertise: General and Ornamental Horticulture; Pest Management; Pesticide Use


Hannah S. Berisford, CPH
Dayton, MD 21036
Areas of Expertise: Greenhouse Production; General Horticulture; Floriculture;Fertilizer Use

My career and love for horticulture began in high school when I started a job at a local garden center my junior year. After that, deciding what to major in during college was easy and I graduated in 2012 with a B.S. in Horticulture from Penn State University. Through out my 4 years in college I held a wide range of jobs and internships ranging from a Horticulture Professional Intern at Walt Disney World to a Wedding Consultant at local flower shop. Currently, I run a greenhouse where we job train adults with developmental disabilities and provide therapeutic horticulture services. I have been with them for 4.5 years and can proudly say I have my dream job. Growing up with a special needs brother created a very special place in my heart for people like him and I am so grateful to be able to combine two very important aspects of my life into a job I love.

Christopher Forth, CPH, CPAg, CCA, VA Nutrient Planner
Bel Air, MD 21015
Phone: 443.868.3223 • Fax: 901.597.0071
Areas of Expertise: Turfgrass Management; Ornamental Horticulture; Fertilizer Use; Pest Management

Chris Forth began his career with ChemLawn, now TruGreen as Lawn Specialist, managing a 35 acre turf and landscape plant research farm and working as Region Technical Manager for 32 years supporting branch operations in DE, MD, NJ, NC, PA and VA. His work has included design and implementation of lawn and landscape maintenance programs for commercial and residential properties, development of and conducting technical training, regulatory compliance and public relations. In 2013, Chris was appointed Technical Training Manager with responsibility for development and delivery of technical training for the newest associates with focus on landscape plant maintenance and care.


Steven A. Van Natta, CPH
350 Hilltop Ave., Owatonna, MN 22060
Phone: 507.451.4144 • Fax: 507.451.7004
Areas of Expertise: Fertilizer Technology; Irrigation & Drainage; Soil Management; Turfgrass Management 


Gary R. Bachman, PhD
Coastal Research & Extension Center
Mississippi State University
1815 Popps Ferry Road, Biloxi, MS 39532
Phone: 228.546.1009
Areas of Expertise: Nursery Management, Horticulture (general), Ornamental Horticulture, Greenhouse Production

Richelle A. Stafne, CPH

13 Woodridge Ln
Picayune, MS 39466
Phone: 601-798-9434  

Areas of Expertise: General and Ornamental Horticulture


Lala A. Kumar, CPH
404 NE Victoria, Lee Summit, MO 64086
Phone: 815.252.5051
Areas of Expertise: General and International Horticulture; Olericulture; Pomology

New York

Elizabeth Berkheiser, B.S., M.L.A., CPH
Plant Palette
PO Box 539, Stony Point, New York 10980
Phone: (631) 839-6039

Areas of Expertise: Ornamental Horticulture

Elizabeth Berkheiser is an ornamental horticulturist and landscape designer who partners with landscape architects, commercial developers, and residential homeowners to create, beautify, and embellish exterior spaces. A sustainable approach to choosing the right plant material for each individual location promotes a healthy longevity to her plant palettes. Her projects vary from residential plots and rooftop gardens, to parks and extensive commercial properties. Liz holds a bachelors degree from The State University of New York at Farmingdale where she concentrated her studies in Horticulture and a Masters degree in Landscape Architecture from the City College of New York.

North Carolina

John D. Abbott, CPH
Syngenta Crop Protection
PO Box 18300, Greensburo, NC 27419
Phone: 336.632.7074
Areas of Expertise: Pest Management; Pesticide Use; Product R&D; Weed Science 

Michael C. Barnes, CPH
Duke Biology
130 Science Drive, Rm. 137, Bio. Sci. Bldg.
Duke Box 90338, Durham NC 27705
Phone: 919.328.9475 • Fax: 919.660.7265
Areas of expertise: Ornamental Horticulture, Floriculture, Greenhouse Production 

Christopher L. Gunter, CPH 
North Carolina State University
230 Kilgore Hall Box 7609, Raleigh, NC 27695-7609
Phone: 919.513.2807 •F ax: 919.515.2905
Areas of Expertise: Crop Physiology; Crop Production; Crop Quality; Plant Nutrition 

Michael T. Morrison, CPH
USDA Risk Mgmt.
4405 Bland Road #165, Raleigh, NC 27609
Phone: 919.875.4950
Areas of Expertise: General and Ornamental Horticulture; Nursery Management; Plant Propagation 

Charles B. Williams III, CPH
1101 Upper Reach Dr., Wilmington, NC 28409
Phone: 910.313.6785
Areas of Expertise: Ornamental and International Horticulture; Pesticide Use; Turfgrass Management


Mark A. Webber BCMA, TRAQ, LTE, TechArborA, CPH
Board-Certified Master Arborist & Horticultural Expert
8172 Hemple Road
Dayton, Ohio 45417
Telephone: 937.604.2291

Areas of Expertise: Agriculture; Arboriculture; Botany; Horticulture

Mark Webber is a Board-Certified Master Arborist and a Certified Professional Horticulturist with nearly forty years of relevant professional experience. He provides investigations, reports, and testimony in matters related to tree condition, maintenance and removal; management of nursery, arboricultural, and landscaping operations; and an assortment of horticultural issues. Mark is active in his industry as the Founder/Co-owner of a landscaping, tree care ,nursery production and consulting business. Mark also worked for some time as a Research Assistant for the BASF Corporation involving fungicides, insecticides, and herbicides and as an Apiary (Honey Bee) Technician for The Ohio State University. Mark earned a Bachelor of Science degree in Horticultural Science with a minor in Agricultural Business from The Ohio State University. He is designated as a Board-Certified Master Arborist by the International Society of Arboriculture, and is a Tree Risk Assessment Qualified Arborist and is a Master Nursery Technician by the Ohio Nursery & Landscape Association. He is also recognized as a TechArborA by the UK’s Arboricultural Association, a New Jersey Licensed Tree Expert, and a Licensed Arborist in multiple states. The board of the American Society of Horticultural Science has designated Mark as a Certified Professional Horticulturist.


Janet C. Cole, CPH
Oklahoma State University
Dept. of Hort., 360 Ag Hall, Stillwater, OK, 74078-6027
Phone: 405.744.5770
Areas of Expertise: Ornamental Horticulture; Nursery Management 


Dong-Man Khu, PhD, CPH
215 S. Abbey Ln., Stillwater, OK 74074
Phone: 269.370.5911
Areas of Expertise: General Horticulture, Plant Breeding, Plant Genetic, and Seed Production

James E. Motes, CPH
2819 E. Richmond Rd., Stillwater, OK, 74075-1766
Phone: 405.372.4634
Areas of Expertise: Best Management Practices; Crop Production; General Horticulture; Olericulture 

Albert J. Sutherland, CPH, CCA
OSU Mesonet Agricultural Coordinator, OSH Biosystems and Agricultural Engineering National Weather Center
120 David L. Boren Blvd., Suite 2900, Norman, OK 73072-7305
Phone: 405.325.3463 • Cell: 405.974.1977
Areas of Expertise: Agricultural Climatology; Computer Uses; General Horticulture 

Steve Upson
924 Souix Street, Ardmore, OK 73401
Phone: 580.224.6433 • Fax 580.224.6420
web: The Samuel Roberts Noble Foundation
Areas of Expertise: Irrigation; Olericulture; Small Fruit Culture; Soil Fertility


Robert E. Call, CPH
Bear Creek Orchands, Inc.
2500 South Pacific Highway, Medford, OR 97501
Phone: 541.864.3514
Fax: 541.613.4198
Areas of Expertise: Areas of Expertise: Pomology, Commercial Orchard Production, Master Gardening Curriculum and Instruction.
• In house consultant for commercial production of 2,000 acres of gift quality peaches and pears. Production manager for 800 acres of commercial apple and cherry.
• Manage all aspects of cucurbit pre-breeding program including research, seed production and worldwide research seed distributions.
• Managed and maintain a germplasm collection of over 9,000 cucurbit accessions.
• Published 38 peer reviewed research papers and Cooperative Extension publications.
• Performed field research and trials of experimental fruit, ornamental and vegetable cultivars.
• Performed field research and delivered efficacy data for six EPA pesticide registration packages.
• Creator and editor of Arizona Master Gardener Manual (908 pages), and author of five chapters.
• Organized professional meetings, conferences and seminars, and many technical presentations.
• Managed all field production aspects of an 800 acre commercial apple and cherry orchard.
• International horticulture consultant in the Dominican Republic, Egypt, Kyrgyzstan, Lebanon, Mexico and Tajikistan.
• Supervised and managed 132 employees and 754 Extension Master Gardener Volunteers.
• Managed $1.6 million annual orchard production budget.
• Total Grants, Gifts and Contracts secured for University of Arizona Extension: $1.9 million.


Don Richards, President, CPH
Applied Horticultural Consulting, Inc.
PO Box 2355, Lake Oswego, OR, 97035-1420
Phone: 503.756.5198
Fax: 503.699.9366
Areas of Expertise: Crop Marketing; Horticulture; Ornamental Nursery Management 

Clinton C. Shock, CPH
Oregon State Univ., Malher Expt. Station
595 Onion Ave., Ontario, OR, 97914
Phone: 541.889.2174
Areas of Expertise: 
Best Management Practices; Crop Ecology; Crop Production; Irrigation and Drainage


John S. De Noma CPH
510 Rittenhouse Blvd., Norriston, PA, 19403
Phone: 610.322.7375
Areas of Expertise: Ornamental Horticulture; Pesticide Use; Soil Fertility; Turfgrass Management 

Michael D. Orzolek, CPH
The Pennsylvania State University
203 Tyson Bldg., University Park, PA, 16802
Phone: 814.863.2251
Areas of Expertise: Crop Production; General Horticulture; Olericulture

Puerto Rico

Christian W. Torres Santana, MS, CPH
Doña Inés Park Arboretum
Luis Muñoz Marín Foundation
RR 2, Box 5
San Juan, PR 00926
LinkedIn profile:
ResearchGate profile:
Areas of Expertise: Native plants propagation, pollination ecology, reforestation in natural areas, garden plantings, and endangered plants conservation and research. He is a Senior Horticulturist, a Botanist, and an Arborist with over 15-years of experience working with tropical plants in the Caribbean and the Pacific Islands.

South Carolina

Michael T. Martin, Jr.
432 Boys Acres Drive, Seneca, SC 29678
Phone: 864.710.8934
Areas of Expertise: Plant Physiology, Plant Propagation, Nursery Management, Ornamental Horticulture


Dilip Nandwani, CPH
Tennessee State University College of Agriculture
Lawson Hall Room 106(B)
Nashville, Tennessee 37209
Areas of Expertise: Tissue Culture (Micro and Macro Propagation); Molecular Biology; Plant Pathology

Robert Richardson, CPH
210 St. James West
Cookville, TN 38501

David Vandergriff, CPH
University Extension - Knox County
City County Bldg., 400 W. Main St., Suite 560, Knoxville, TN 37902-2411
Phone: 865.215.2340


Gregory T. Church CPH
16 Steel Road
Wylie, Texas 75098
Phone: (972) 442-1524; (972) 429-0012 (fax)
Areas of Expertise: Plant Pathology; General and Ornamental Horticulture; Pest Management 

Leslie Halleck, CPH
Halleck Horticultural
9540 Garland Rd. Ste. 381-342
Dallas, TX 75218
Phone: 469.906.6074
Areas of Expertise: General Horticulture, Garden Center Management, Ornamental Horticulture, Plant Ecology.

Halleck is a dedicated horticulturist with 27 years of green industry experience. She earned her MS in Horticulture at Michigan State University and her BS in Biology/Botany from the University of North Texas. Her previous positions include Director of Horticulture Research at the Dallas Arboretum, where she was responsible for creating and developing their well-known plant trials program, as well as establishing an All-America Selections Garden. As well as General Manager for North Haven Gardens, a well-respected independent garden center in Dallas. She currently runs her own company, Halleck Horticultural, through which she provides horticultural consulting for growers, commercial and residential projects, landscape architects, landscape designers, and property managers – and consults with green industry companies on business and product development, horticultural marketing and branding, digital projects, content generation, and company culture.

Halleck is the author of several books for gardening consumers, including “Gardening Under Lights; The Complete Guide for Indoor Growers”, 2018, and “Plant Parenting; Easy Ways to Make More Houseplants, Vegetables, and Flowers, 2019. She has been a monthly columnist for the past 8 years for Garden Center Magazine, Greenhouse Management Magazine, and Produce Grower Magazine.


Leon R. Macha, CPH
1304 Meadow Creek Dr., El Campo, TX, 77437
Phone: 979.543.2445 • Cell: 979.320.4434
Areas of Expertise: General and Ornamental Horticulture; Nursery Management


Terry G.L. Ferriss, CPH
University of Wisconsin-River Falls
307 Ag. Science, River Falls, WI, 54022
Phone: 715.425.3535
Areas of Expertise: Floriculture; General Horticulture; Greenhouse Production


David C. Zlesak, Ph.D.
Professor of Horticulture, 2017 UWRF Distinguished Teacher
UWRF Plant and Earth Science Department
410 S. 3rd Street
River Falls, WI 54022
Office: 715-425-4415; Cell: 763-486-7920

Areas of Expertise: Ornamental Horticulture; Plant Breeding; Plant Propagation, Tissue Culture


Lise Pittman Foy, CPH
Executive Director, Rooted in Wyoming
PO Box 625
Dayton, Wyoming 82836
Phone: (662)-858-0279
Areas of Expertise: General Horticulture, Education, Agritourism, Landscape Design

I am the incoming Executive Director for a non-profit organization called Rooted in Wyoming. Our mission and vision are as follows:
Mission: Rooted in Wyoming partners with community organizations and schools to facilitate outreach programs and cultivate educational gardens.
Vision: Rooted in Wyoming envisions a future where everyone in our state has access to fresh local foods and is motivated to grow their own food.
Since 2004, it has been my goal to inspire people to appreciate and enjoy the tremendous beauty of the diverse plant world. It is also my ambition to be a life-long student of all the many facets of horticulture. My education needs have become directed at learning to teach kids and volunteers about horticulture, and helping to find appropriate and useful resources for schools and garden leaders.


Karen L. Panter, CPH
Univ. of Wyoming, College of Agr., Dept. 3354
1000 E. Univ. Ave., Laramie, WY, 82071
Phone: 307.766.5117

Casey P. Seals, CPH
1766 N 18th Street
Laramie, WY 82072
Areas of expertise: Garden Center Management, Greenhouse Production, Horticulture, General, Irrigation

Outside the United States


Jeffrey P. Norrie, CPH
15693 Highway 4, Wentworth, NS, B0M1Z0, Canada
Phone: 902.441.7487

Areas of Expertise: General Agronomy; Plant Physiology; Crop Science; Greenhouse Production

Jeff grew up on a beef farm in rural Nova Scotia, Canada. His BSc (Mount Allison, 1985) focused on animal physiology and marine sciences with minors in plant physiology and biophysics. His MSc (Dalhousie, 1988) examined environmental and plant hormone interactions in Integrated Cereal Management research. His PhD (Laval, 1992) involved research on greenhouse crop nutrition and automated fertigation systems while his post-doctoral research looked at soil amendments and fertility management in Turf and Ornamentals. Jeff has served as the Agricultural Research Manager for Acadian Seaplants Limited (ASL) since 1995. Based in Dartmouth, NS, ASL is an innovative company specializing in marine plant products for the Asian food market, the botanical industry, feed/food ingredients and the fertilizer/biostimulant industry. Jeff currently oversees programs in international fundamental and applied research, and provides technical support on the use of marine plant products and extracts the world over. With the help of French and Spanish he picked up along the way, Jeff’s networking, seminars and projects take him into over 40 countries. He is active in several professional societies having served as president of the Nova Scotia Institute of Agrologists, the Plant Growth Regulation Society of America, and he’s currently a VP with the American Society for Horticultural Science. All told, Jeff’s passion remains in connecting grower concerns with researcher solutions, and helping to build sustainable crop programs in both advanced and developing countries. He currently works with Breathing Green Solutions in Nova Scotia.

Muhammad Saeed

Proplant Propagation Services, Ltd.
2401 Hwy #6, Jarvis ON N0A 1J0
Phone: 519.587.2235 • Fax: 519.587.2236 • Cell: 519.410.5665

Areas of Expertise: Greenhouse Production; Plant Propagation; Plant Physiology; Nursery Management


Jim Hole, CPH
101 Riel Drive
St. Albert, AB T8N 3X4
Phone: 780-419-6802
Fax: 780-459-6042

1018 Duke Street
Alexandria, VA 22314
Phone: 703.836.4606